Production of esters



@QL EL i932. R HELD ET AL l LSSLSE PRODUCTION OF ESTERS Filed Nov. 30, 1929 Patented Oct', 11, 1932 QNITED STATES PATENT? QFFICE l ROBERT HELD', or orPAU, AND MARTIN LUTHER, 6E MANNHEIM, GERMANY, ASSIGN- ons To I. e. rAHEENINnUsTnIE AKTIENGESELLSCHAFT, or rnANxronT-oN-THE- MAIN, GERMANY rnonocTIoN or EsTEEs Application led November 30, l19119, Serial No. 410,773, and in Germany December 15, 1928.

The present invention relates to the production of esters. v

In the method of working hitherto usually employed the esteriiication of organic acids with alcohols, for example of higher -fatty acids with glycerol, takes place very slowly,

, and. in practice, even when employing a vigorously- 'operated stirring device, 'comparatively long periods of time are necessary for i ,-visionyfof large surfaces the process is considerably facilitated; as regards the removal' ofgtherwater formedy during-the reaction.,

I' Bodies of -an inert material for example balls or lumps of glass, porcelain,

coke or pumice and the like, or sieves may :be-em loyed andalso such bodies which contssi'stgo or comprisel catalytically active subl ylstances?accelerating th ejremoval of water hev temperature of y active carbon and the like.- 'Catalystssug salts of the higher fatty acids may also` be mixed with the reacting components. fIt is advantageous to operate with the employment of a vacuum.

` By the processes hitherto known forthe manufacture and production of esters from alcohols and acids, for example of glycerides of higher fatty acids, it has been usual to work with an'excess of alcohol or an excess of acid in order to obtain neutral products, and in each case the excess is removed from the reaction mass at the end of the reaction in any known and suitable manner.

A practically neutral esterifica'tion product which is also free from non-esteriiied alcohol may be obtained according to the present invention when' the acid and the aland ,thereby-2 reducm working-,such as a cohol are employed in such amounts that'the component having the lower boiling point is present in excess, the reacting components bemg led, preferably 1n a continuous operation, through reaction zones provided with bodies possessing a large superficial area, as

hereinbefore described, the temperatures of the 'said zones being increased in stages in the direction of flow of the liquids, the temperature of atleast the last zone being above the boiling pomtxof the component of lower boiling point but below the boiling point of vthe component of higher boiling point at the pressure employed.

The nature of this latter method will be further described with reference to the accompanylng drawing which shows diagrammatically an arrangement of apparatus according to this invention, but the invention is not restricted to this, arrangement.

The apparatus comprises a closed reaction tower T'provided at its top with inlet pipes J1 and J 2 connected with storage vessels A and B, the inlet pipe J2 reaching down to about the bottom of the middle zone 2 of the tower, the tower being charged with acid proof bodies F possessing a large superficial area. and is provided with external (or internal) means H for electric heating subdividing for example the interior of the tower into zones 1, 2 and 3. The tower Tis-:further provided near its top with ari-:foil et C and near its bottom with an outltpi D. The process in accordance with the' present invention may be carried out for example by introducing the acid, which is t0 be eStQr -v fied, from the vessel A through the inlet pipe J1 at the top into the reaction zone 1, while the alcohol is introduced from the vessel B through the inlet pipe J 2 into the reaction zone 2 which is heated to a higher temperature than the reaction zone 1. For example in the manufacture ofl glycerides of higher fatty acids the tem erature in the zone 1 is kept at about 160 at about 190 C. In this case the glycerol vapour rising from the Zone 2 meets the hot fatty acid, and in this manner a combination of the glycerol by esterification with the splitting oif of water takes place and the water streams out through the outlet C'in the form of steam. The removal of the water and in zone 2 grains of pumicestone y y in such'a mannerthat-'theltemperaturerinthe tated by inthe drawing,

vfree acids `may from the reaction chamber may be faciliconnecting vthe outlet C with an evacuating device. The esteriication of any free acid which may still be present takes place in the lower zone 3, which is heated to a temperature of from 220 to 230 C. where at the same time any glycerol which is' carried along with the reaction product liowing down from the reaction zones 1 and 2 is vapourized. The glycerol vapour streams back into the upper partl of the tower. The reaction product is withdrawn from the bottom of the tower through the pipe D, and it constitutes a ractically acid-free neutral oil. A s ecial a vantage of the process in accor ance with the present invention resides in the fact that in contrast to the processes already known the reacting materials are only exposed to high temperatures for a comparatively short period of time and are therefore protected to a very great extent.

vThe following examples will further illustrate the nature of this invention, but the invention is not restricted to these examples. The parts are by weight.

Example 1 and which is charged withl granular cokev and heated to a temperature of .from 180 vto 200 C. The pressure prevailing inthe tower amounts to from 10 to 20 millimetres of mercury. The ester formed is withdrawn at the lower part of the tower, and is washed and freed from the remainders offree acid.

fatty acids of olive oil an olive oil containing also be'employed. 'ffE'ampZe-'2- y milan r`to i that" shown belg' iwhich isabout first zone amounts -to l160'G.,.initwhe' second to 190 C. `and A.in the third to 220 (lisv 500 parts of olive oilfattyacid jare introducedfinto the {irst'zone and 100 parts of y1'fglycerol into the `second zone.` f The reaction i product which runsol at -thebot'toin ofthe tower is free from glycerol yand consists to the cxtentof over 96 per cent ofneutral oil. Theremainders ofl glycerol are carried oil Lacasse of fatty acids and polyhydric alcohols which lcomprises causin the acid and the alcohol to be esterified to ow in the liquid state over solid inert bodies possessing a large superficial area, while heating.

2. The process for the production of esters of fatty acids and polyhydric alcohols, which comprises causing the acid and the alcohol to be esterfied to liow in the liquid state over solid inert bodies possessing a large superficlal area, while heating, the component of lower boiling point being present in a quantity in excess of that required'for complete esterication of the other component.

3. The process for the production of esters of fatty acids and polyhydric alcohols, which comprises causing the acid and the alcohol to be esteriiied to flow in the liquid state over solid inert porous bodies possessing a large superficial area, while heating.

4. The process for the production of esters of fatty acids and polyhydric alcohols, which comprises causing the acid and the alcohol to be esteriied to flow vin the liquid state over vsolid inert bodies possessing a large superficial area in thel presence of a catalytic substance capable of accelerating the esterification, while heating. j

'5.- The process for the production of esters ot fatty acids, which vcomprises causing a hlgher .nfattyjacid and polyhydric alcohols 'and a polyhydric alcohol to How in the liquid state over solid inert bodies possessing a large superlicial'area, while heating. i

6. The process for the production of esters otfattyacids and polyhydric alcohols,which comprises causinga higher fatty acid and locl glycerol. to flow in the liquid state over solid inertbo'dies possessing ay large superficial area, whileheating.

7. The process for the production of esters 'V-.of :fattyacids'and polyhydric alcohols, which comprises causing the `acid and lthe alcohol tobe'esterilied to lHow in the liquid state over -'solid inert bodies possessing' a large Superlicial ja'reaat a temperatureabove'lthe boiling f. point of the component of lower boiling point `ut below the boiling point of the component of higher boiling point at the pressure employed'. v

. f8; The'fpijocess foru the .production of esters flcf'higlier*fattyfacids and polyhydric alcohols, which comprises introducing the component of lower boiling point in the liquid "state into about the middle zone of a column of the component of higher boiling point contained in a suitable vessel and heated to a temperature near the'boilingpoint of the component of lower boiling point, in the presence of solid inert bodies of a large superfcial area, a zone below the said middle zone being heated to a temperature above that of the said middle zone, but below the temperature of decomposition of the organic substances present- 9, The process for the production of esters of higher fatty acids and polyhydric alcohols, which comprises introducing the component of lower boiling point in the liquid state into about the middle zone of a column of the component of higher boiling point contained in a suitable vessel and heated to a temperature near the boiling point of the component of lower boiling point, in the presence of solid inert bodies of a large superficial area, a zone below the said middle zone being heated to a temperature above that of the said middle zone, but below the temperature of decomposition of the organic substances present, and a zone above the said middle zone being heated at least to a temperature above the boiling point of water at the pressure employed.

10. An apparatus for carrying out the process claimed in claim 8, which com rises a tubular closed reaction vessel provide with subdivided heating devices for heating diierent portions of the said vessel to different temperatures and filled with inert iiller bodies of lar e superficial area, the top of the said vessel eing provided with a short inlet pipe and with an inlet pipe reaching about into the middle space of the said vessel which vessel is provided with an outlet pipe each at its bottom and near its top.

11. The process of forming a fatty acid ester which comprises effecting the esteriication in a tower having a plurality of superposed interconnected zones by introducing the acid into the uppermost zone while heating this zone to a temperature above the boiling point of water to prevent the condensation of water therein, introducing the alcohol into the next succeeding zone While heating this zone to a temperature above the boiling point of the alcohol, causing the alcohol to contact the descending acid while finely dividing' the acid and imparting a large surface area of contact thereto to thereby effect interreaction of the acid and alcohol, causing the reaction mixture to iow into the lowermost zone while imparting a large surface area of contact to the constituents thereof and heating this zone to a temperature higherv than that of thepreceding zone, but below the decomposit-ion point of the constituents of the mixture to complete the esterication of the acid and alcohol contained in said mixture.

12. A process as defined in claim 11 where- 1n the esterification is carried out under a reduced pressure.

the esteritication in a tower having three superposed interconnected zones by introducing the acid into the uppermost zone while heating this zonev to about 160 C., introducing the glycerol into the next succeeding zone while heating this zone to about 190 C., causing the glycerol to contact the descending acid while finely dividing the acid and imparting a large surface area of contact thereto to thereby eiect interreaction of the acid and glycerol, causing the reaction mixture to How into the lowermost zone while imparting a large surface area of contact to the constituents thereof and heating this zone to a temperature of about 220 C. to complete esterication of the acid and glycerol contained in said mixture, the three zones being maintained under a pressure of about 15 millimetres during the process. p

In testimony whereof we have hereunto set our hands.

ROBERT HELD. MARTIN LUTHER.

13. 4The process of forming a glyceride of 1 

